An IC handler has been in common use as a semiconductor tester. In the IC handler, an IC transferred from the IC loader is placed on the socket of the measuring section. In this state, the pusher of the test hand presses the IC against the socket to bring the contact section of the IC, such as the lead pins, into contact with the contactor of the socket. From the result of electric conduction, the tester judges whether the IC characteristic is acceptable. Then, the unloader separates the IC from a reject and holds it.
In recent years, the types of ICs to be tested have been diversified and consequently the types of sockets to hold them have also been diversified. Thus, the operating performance of the test hand should be changed so as to deal with the type of IC. Since the semiconductor tester is requested to process many ICs in a short time, it is desirable that the IC handler should function at high speed. However, the faster the processing speed becomes, the more increase the impact of the pusher on the IC when the pusher is pressed against the IC, and thus the service life of the lead pins of the IC and the socket. contactor may become shorter.
To overcome those problems, a handler, which has been disclosed in Jpn. Pat. Appln. KOKAI Publication No. 9-89983, is developed. In this handler, the data of allowable contact pressure in each type of IC has been inputted in a FD (floppy disk) beforehand. When the operator specifies the type of IC, the CPU sends a signal to the control valve on the basis of the data from the FD, thereby the hydraulic cylinder pressure for driving the test hand can be adjusted.
Furthermore, Jpn. Pat. Appln. KOKAI Publication No. 10-227834 has disclosed a mechanism for making fine adjustments to the proper pressure, speed, and displacement of IC pressed into a socket according to the type of IC.
In the above methods currently in use, however, it is required to input IC handler data for each type of IC into the computer in advance. And what is more, these data may be obtained through experience based on the pin pressure per lead pin, the number of pins and the allowable displacement of the socket contactor.
However, since the IC is pressed down by the test hand as it is in a socket, it may not be assured that the values based on the specified data items are always proper. For example, as the working speed of the test hand is increased to process the IC at high speed, the impact on the IC happens and becomes larger when the test hand hits the IC package. In addition, the impact force is likely to exceed the material strength of the IC leads or socket contactor and do damage to the IC package.
Accordingly, the object of the present invention is to provide an operation method and system for an IC handler to control properly the pushing pressure, operating speed and displacement of the test hand according to the types of IC and socket.
To achieve the foregoing object, the operating method of the working of test hand to control appropriately the pushing force, operating velocity and displacement thereof in the IC handler is invented.
In order to realize the above-mentioned object, the control method of the test hand for pushing the contact of the IC on the socket of the IC handler comprises the step of measuring data by means of sensors through the trial to press an IC on the socket repeatedly by the test hand, so as to obtain data representing the load, the acceleration or velocity, and the amount of thrusting displacement of the test hand until the stoppage thereof after the tip of the test hand contacts with the IC; obtaining the combined spring constant K of the IC socket; and determining the motion of test hand so as to work the impact force to an IC becoming smaller than the allowable press force.
Furthermore, a control system of the present invention comprises a load sensor for detecting the press force of the test hand applied to an IC; an acceleration sensor for detecting the operating velocity or acceleration of the test hand; a displacement sensor for measuring the thrusting displacement during the time from when the test hand comes into contact with the IC until it stops; and control means for not only calculating the combined spring constant for the IC and a socket on the basis of the data items from the individual sensors, but also controlling the driving of the test hand on the basis of the individual data items so that the press force, velocity, and displacement may reach such values that make the impact force acting on the IC equal to or smaller than an allowed value and speed up the operation of the test hand to the maximum.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.